As can be seen in FIG. 3, an absolute pressure gauge having a capsule element as pressure element, wherein the zero point of a measurement display can be adjusted in a mechanical way after a test vacuum has been applied, is known. The zero point adjustment according to said state of the art is effected by means of a pinion engaging with a gearwheel which is part of a display adjustment device of a manometer. The pinion is turnably accommodated in a mount which is inserted into an outer casing of the manometer and is fixed to it by means of welding before the manometer is assembled. An O-ring between the pinion and the mount seals the manometer, and a threaded nut screws the one end of the pinion where a thread is provided to a sidewall of the mount, in order to fasten and secure the pinion.
In order to enable a zero point adjustment in the above described absolute pressure gauge according to the state of the art, the threaded nut must be loosened before the pinion can be turned, i.e. before the zero point can be adjusted. This leads to the fact that the adjustment procedure of the manometer is time-consuming and tedious.
Furthermore, the pinion must be inserted into the mount before the manometer is assembled, said mount is then positioned in a bore hole in the outer casing of the manometer and is then welded to the outer casing.
This special design of the manometer requires a manual-labor-intensive assembly of the individual components consisting in many single and individual steps. Therefore, a production process of the absolute pressure gauge becomes labor-intensive and thus expensive.
Thus, it is the object of the invention to provide a simple and quickly to adjust pressure gauge. In accordance with the invention, this object is achieved by means of a pressure gauge having the features of claim 1.